Integrated circuit fabrication may involve formation of a photolithographically-patterned mask over a semiconductor substrate, followed by transfer of a pattern from the mask into one or more materials with one or more etches.
The photolithographically-patterned mask may comprise any suitable radiation-imageable material, such as polyimide or photoresist. A pattern is formed in the radiation-imageable material by subjecting the material to patterned actinic radiation (for instance, ultraviolet light) so that some portions of the radiation-imageable material are exposed to the radiation while other portions are not exposed. Either the exposed or unexposed portions may be selectively removed relative to the other of the exposed and unexposed portions with an appropriate developing solution, thereby creating a pattern in the radiation-imageable material.
A continuing goal of integrated circuit fabrication is to create smaller structures. Numerous difficulties may be encountered in attempting to create smaller structures with traditional photolithographic processing, in that a minimum size achievable by a photolithographic process is imposed by the wavelength of actinic radiation utilized in the process. Modern processes are approaching the limits of scalability imposed by the physical properties of the actinic radiation.
It would be desired to develop new methods of forming patterns for integrated circuit fabrication which can extend the limits of scalability.